Question for Greg M. re.Contrabass sub

Discussion in 'Archived Threads 2001-2004' started by James W. Johnson, Jul 2, 2001.

  1. James W. Johnson

    James W. Johnson Screenwriter

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    Greg, what all is needed for a contrabass sub?
    There are 4 items listed on the website, do I
    need the CB Kit and the Servodrive motor?
    It looks like the other two items are cabinets.
    http://www.earlym.com/pages/kits.html
    Contra Part #: Price
    1.) CB Kit $764.50
    2.) 18-9000 $440.00
    3.) 88-1001 $660.00
    4.) 18-9001 $440.00
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    James' DIY speakers
     
  2. Julian Data

    Julian Data Second Unit

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  3. Greg Monfort

    Greg Monfort Supporting Actor

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    You need the kit, 88-1001 motor, and a cab that you can build.
    GM
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    Loud is beautiful, if it's clean
     
  4. James W. Johnson

    James W. Johnson Screenwriter

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    So a contrabass is pretty damn expensive...of course I have to ask how would a single Contra stand up to a dual Stryke sub?
     
  5. Jack Gilvey

    Jack Gilvey Producer

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    James, there's some discussion of that on the last page of this thread:
    http://www.avsforum.com/ubb/Forum3/HTML/004849-2.html
    A quote from Mark Seaton:
    quote: Many designers still refference the capabilities of their subwoofers to the now 15 year old Contrabass, and for it's size, nothing has yet matched its high output and low distortion and thermal compression. The dual HE15 Bob has is the only configuration I know of which can out-displace it, but requires ~6-10x the power and has more distortion at those levels.[/quote]
     
  6. James W. Johnson

    James W. Johnson Screenwriter

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  7. James W. Johnson

    James W. Johnson Screenwriter

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    Thanks for the link Julian, I can really get the cost down on a Contrabass if I buy a different servo motor and build my own enclosure..
    In fact I figured I could do it for less than $1000
    Furthermore I will not have to buy another amp, my Mackie M-100 should be sufficent enough.
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  8. Mark Seaton

    Mark Seaton Supporting Actor

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    Mark Seaton
    James,
    It's not "quite" that simple. With the surplus motor you do have to be concious of the amplifier you are using, or you need to use an autoformer. The alternate motors tend to have DC resistances around 1 Ohm, and will draw a good deal from your amps. The somewhat unique, high impedance of the ServoDrive motor is one of a few reasons for its high cost.
    On to the sound. First, yes, the Contra will play louder than your dual Tempest down low, and be MUCH cleaner at higher outputs. The Tempests can actually take more power in the upper bass range, but the Contra will sound much cleaner doing what it does. IMHO, a pair of Contras would better suit your desires. Note that the sub also has a rather unique characteristic where there is not the gradual onset of distortion as is seen with VC driven subs, but rather it hits the suspensions limits and distortion comes on quite quickly. You will RARELY hit this when playing music, but if you go to test what it can do, it may not "sound" quite as loud to you without all the distortion products. It is actually quite a unique thing to hear, where you can have deep bass reproduction without all the added harmonics from the distortion of most subs. Most systems "voice" the bass balance to account for this sound, where the Contra doesn't react in this way.
    Jack, thanks for posting that quote, and one more time I would re-itterate the issue of harmonic and IM distortion, and particularly thermal/power compression. What makes this possible is the in-difference of the motor to it's position. It is just as linear at full excursion as it is at 1/4 that. The only flaw in the design is the slight noise generated by the brushes in the motor, which become mostly in-audible at more than 1M away. I need to talk to Tom Danley about it, but I was thinking that double or triple thick MDF could be sufficiently rigid, and possibly better isolate the brush noise.
    Mark Seaton
     
  9. Greg Monfort

    Greg Monfort Supporting Actor

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    >I can really get the cost down on a Contrabass if I buy a different servo motor and build my own enclosure.
    =====
    Good luck finding any of these motors, and if you do please share the info with me, and note MS's exceptions. Mine are 0.89ohm, so unless the amp can do double duty as an arc welder.....
    WRT two in a typical room, I just don't see the point unless you're like me and prefer 'stereo' subs and/or want/need enough infrasonic headroom to boost the
     

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